The old horizontal nav used to open the top level menus (i.e. Monitor, Content, Containers) immediately. The new vertical nav has a delay (maybe half a second?) before the menu opens. It should open immediately.

The delay is either too long, or the menu should respond immediately to clicks. As a user, it feels like I'm wasting time waiting on the menu to open. Also, the horizontal navigation has always opened immediately, so I would think that users are accustomed to that behavior. Is this delay a result of feedback from UX trials? I would be curious how many users out of the group commented on this aspect of the menu.

So, I did some research, and patternfly doesn't allow overriding this delay, though there's an issue/feature request to add it [1]. I went ahead and submitted a PR to patternfly [2] to implement the feature, since the conversation on the feature request seemed stale.